Drainage cell consists of 1m x 1m x 30mm squares of injection moulded Polypropylene (PP) that are preferred for the base of planters. The squares are in fact 500mm x 500mm panels that are clipped together but easily separated.
There is no good reason for using on the sides of a planter but laying on protection board is recommended for both the base and sides. 1mm PP filter fabric is normally laid on top and tucked in at the sides. Cut edges could be laid inwards so the membrane is not damaged.
Drainage sheet consists of a dimpled PP sheet available as 8mm x 2m x 20m and 10mm x 1.22m x 5m, with an integrally attached filter fabric for the dirt side. They are normally used on vertical walls when the back fill is not porous.
To avoid the membrane being literally washed away, the top of the sheet should terminate under a flashing. This means that facade water should be drained separately.
The sheets are best fixed mechanically with Wrimco 5 x 25 angle at the top with 150-200mm overlaps. There must be no joints that have to be nailed through the membrane so the drainage sheet must be hung from the top in one piece.